As we’ve been following here at InvestorPlace, the hydraulic fracturing and horizontal drilling revolution continues to spread across North America’s shale formations. From coast to coast, the advanced drilling techniques have unlocked some of the world’s most prolific oil and natural gas reserves.

However, while the opportunities in some regions like the Bakken and Marcellus are great, they are pretty well-known at this point. The initial land rushes and subsequent surges in E&P firms’ share prices have all but faded. These plays are now about steady production and cash flows for operators.

But for investors, finding the next “big shale play” before the word gets out could be the secret to outsized energy gains. And one such potential gusher for portfolios could lie within the fertile Eagle Ford’s little brother in the east.

The Region

Petrohawk Energy first drilled in the Eagle Ford in Texas back in 2008, and it quickly went from virtual obscurity to being one of the biggest oil producing regions in the U.S. after the Permian Basin and the Bakken.

The Eaglebine, on the other hand, is located in East Texas, about 100 miles northwest of Houston. The focus of the field is the thick, organically rich section of rock located below the Austin Chalk formation and above the Buda Limestone formation that combines the lower Eagle Ford and the Woodbine. That’s fancy geology talk which basically means the Eaglebine is where these two fields butt up against each other. Hence the region’s name.

The Woodbine formation was first discovered in 1930 and is best known as the reservoir which houses the famous East Texas Oil Field. That field has been one of the most productive oil fields in the U.S. In fact, conventional vertical oil wells in the last century produced as much as 200,000 barrels a day of oil equivalent from the region. Like many of the “classic” oil fields in the U.S., horizontal drilling and fracking has given new life to older wells and formations. As such, there’s still plenty of oil and condensate left in the Woodbine sandstone.

That porous rock in the Eaglebine makes fracking quite easy, as lower-horsepower rigs and lower fracking pressures can be used in the drilling process. Additionally, the region’s sandstone geology allows the drilling and completing progression to consume less water and produce less waste. All of that drives costs down to the $5.5 million dollar mark to frack an Eaglebine well. Since 2007, nearly 100 horizontal wells targeting these Woodbine sands have been drilled and producers are seeing success in the Eaglebine’s tight sands.

But, the field’s potential isn’t done yet.

As you get closer to the Eagle Ford side, the geology changes and you have more of a “traditional” unconventional layered shale play, providing a different set of risks and rewards for E&P firms willing to tap this side of the shale play. More importantly, those laminated shale rocks are heavily tied to oil and NGLs — meaning energy firms get higher prices for their production.

The Play

While several firms — like EOG Resources (NYSE:EOG), Devon Energy (NYSE:DVN) and Canada’s EnCana (NYSE:ECA) — do have acreage in the Eaglebine, there is only a handful of firms that have made it a focus of their efforts.

One prime example is Halcón Resources (NYSE:HK). The company’s CEO Floyd Wilson was the man behind the success of Petrohawk and the main reason why the Eagle Ford was tapped in the first place. Petrohawk was later sold to BHP Billiton (NYSE:BHP) for $15.1 billion and a hefty gain for shareholders.

Aside from sharing the former hawk’s ticker symbol and name — halcón is a Spanish word for falcon — the firm is also operating in the same spirit.

It currently owns and operates 235,000 acres in the Eaglebine/Woodbine region, with nine wells in the field so far along with plans to operate five to seven drilling rigs and spend approximately $490 million on fracking and completions this year. The company plans on “spudding” — or starting — 60 to 70 wells in the Eaglebine by the end of 2013. That should help drive future revenue gains and growth at the energy firm.

Not that it has had too much trouble in the growth department.

Halcón grew its reserve base by a staggering 417% and its daily production by 128% in 2012. Most that growth has come from HK’s Bakken acreage. However, if its holdings in the Eaglebine turn out to be even half as good as expected, investors can expect its share price to surge.

So far, HK share price has averaged 13% losses over the last five years … but that was before Wilson came on board and reinvented firm the firm. Already, Wilson has made his intentions on building Halcón into a buy-out target for another major publicly known.

The bottom line is that the Eaglebine represents one of the biggest emerging unconventional plays in North America. For investors, Halcón Resources — whether via a buyout or increased production — could be the best way to play the region’s oily potential.

As of this writing, Aaron Levitt did not hold a position in any of the aforementioned securities.